Apparatus for patterned plasma-mediated laser ophthalmic surgery

ABSTRACT

System and method for making incisions in eye tissue at different depths. The system and method focuses light, possibly in a pattern, at various focal points which are at various depths within the eye tissue. A segmented lens can be used to create multiple focal points simultaneously. Optimal incisions can be achieved by sequentially or simultaneously focusing lights at different depths, creating an expanded column of plasma, and creating a beam with an elongated waist.

CROSS-REFERENCE

This application claims priority to and is a continuation of U.S. patentapplication Ser. No. 14/949,645, filed Nov. 23, 2015, which is acontinuation of U.S. patent application Ser. No. 14/742,663, filed Jun.17, 2015, which is a continuation of U.S. patent application Ser. No.14/184,047, filed Feb. 19, 2014, which is a continuation of U.S. patentapplication Ser. No. 13/588,966, filed Aug. 17, 2012, which is acontinuation of U.S. patent application Ser. No. 11/328,970, filed Jan.9, 2006, which claims the benefit under 35 U.S.C. §119(e) of U.S.Provisional Patent Application No. 60/643,056, filed Jan. 10, 2005, thefull disclosures of which are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to ophthalmic surgical procedures andsystems.

BACKGROUND OF THE INVENTION

Cataract extraction is one of the most commonly performed surgicalprocedures in the world with estimates of 2.5 million cases beingperformed annually in the United States and 9.1 million cases worldwide.This is expected to increase to approximately 13.3 million cases by 2006globally. This market is composed of various segments includingintraocular lenses for implantation, viscoelastic polymers to facilitatesurgical maneuvers, disposable instrumentation including ultrasonicphacoemulsification tips, tubing, and various knives and forceps. Moderncataract surgery is typically performed using a technique termedphacoemulsification in which an ultrasonic tip with an associated waterstream for cooling purposes is used to sculpt the relatively hardnucleus of the lens after performance of an opening in the anterior lenscapsule termed anterior capsulotomy or more recently capsulorhexis.Following these steps as well as removal of residual softer lens cortexby aspiration methods without fragmentation, a synthetic foldableintraocular lens (IOL's) inserted into the eye through a small incision.This technique is associated with a very high rate of anatomic andvisual success exceeding 95% in most cases and with rapid visualrehabilitation.

One of the earliest and most critical steps in the procedure is theperformance of capsulorhexis. This step evolved from an earliertechnique termed can-opener capsulotomy in which a sharp needle was usedto perforate the anterior lens capsule in a circular fashion followed bythe removal of a circular fragment of lens capsule typically in therange of 5-8 mm in diameter. This facilitated the next step of nuclearsculpting by phacoemulsification. Due to a variety of complicationsassociated with the initial can-opener technique, attempts were made byleading experts in the field to develop a better technique for removalof the anterior lens capsule preceding the emulsification step. Thesewere pioneered by Neuhann, and Gimbel and highlighted in a publicationin 1991 (Gimbel, Neuhann, Development Advantages and Methods of theContinuous Curvilinear Capsulorhexis. Journal of Cataract and RefractiveSurgery 1991; 17:110-111, incorporated herein by reference). The conceptof the capsulorhexis is to provide a smooth continuous circular openingthrough which not only the phacoemulsification of the nucleus can beperformed safely and easily, but also for easy insertion of theintraocular lens. It provides both a clear central access for insertion,a permanent aperture for transmission of the image to the retina by thepatient, and also a support of the IOL inside the remaining capsule thatwould limit the potential for dislocation.

Using the older technique of can-opener capsulotomy, or even with thecontinuous capsulorhexis, problems may develop related to inability ofthe surgeon to adequately visualize the capsule due to lack of redreflex, to grasp it with sufficient security, to tear a smooth circularopening of the appropriate size without radial rips and extensions ortechnical difficulties related to maintenance of the anterior chamberdepth after initial opening, small size of the pupil, or the absence ofa red reflex due to the lens opacity. Some of the problems withvisualization have been minimized through the use of dyes such asmethylene blue or indocyanine green. Additional complications arise inpatients with weak zonules (typically older patients) and very youngchildren that have very soft and elastic capsules, which are verydifficult to mechanically rupture.

Finally, during the intraoperative surgical procedure, and subsequent tothe step of anterior continuous curvilinear capsulorhexis, whichtypically ranges from 5-7 mm in diameter, and prior to IOL insertion thesteps of hydrodissection, hydrodilineation and phaco emulsificationoccur. These are intended to identify and soften the nucleus for thepurposes of removal from the eye. These are the longest and thought tobe the most dangerous step in the procedure due to the use of pulses ofultrasound that may lead to inadvertent ruptures of the posterior lenscapsule, posterior dislocation of lens fragments, and potential damageanteriorly to the corneal endothelium and/or iris and other delicateintraocular structures. The central nucleus of the lens, which undergoesthe most opacification and thereby the most visual impairment, isstructurally the hardest and requires special techniques. A variety ofsurgical maneuvers employing ultrasonic fragmentation and also requiringconsiderable technical dexterity on the part of the surgeon haveevolved, including sculpting of the lens, the so-called “divide andconquer technique” and a whole host of similarly creatively namedtechniques, such as phaco chop, etc. These are all subject to the usualcomplications associated with delicate intraocular maneuvers (Gimbel.Chapter 15: Principles of Nuclear PhacoEmulsification. In CataractSurgery Techniques Complications and Management. 2^(nd) ed. Edited bySteinert et al. 2004: 153-181, incorporated herein by reference.).

Following cataract surgery one of the principal sources of visualmorbidity is the slow development of opacities in the posterior lenscapsule, which is generally left intact during cataract surgery as amethod of support for the lens, to provide good centration of the IOL,and also as a means of preventing subluxation posteriorly into thevitreous cavity. It has been estimated that the complication ofposterior lens capsule opacification occurs in approximately 28-50% ofpatients (Steinert and Richter. Chapter 44. In Cataract SurgeryTechniques Complications and Management. 2^(nd) ed. Edited by Steinertet al. 2004: pg. 531-544 and incorporated herein by reference). As aresult of this problem, which is thought to occur as a result ofepithelial and fibrous metaplasia along the posterior lens capsulecentrally from small islands of residual epithelial cells left in placenear the equator of the lens, techniques have been developed initiallyusing surgical dissection, and more recently the neodymium YAG laser tomake openings centrally in a non-invasive fashion. However, most ofthese techniques can still be considered relatively primitive requiringa high degree of manual dexterity on the part of the surgeon and thecreation of a series of high energy pulses in the range of 1 to 10 mJmanually marked out on the posterior lens capsule, taking great pains toavoid damage to the intraocular lens. The course nature of the resultingopening is illustrated clearly in FIG. 44-10, pg. 537 of Steinert andRichter, Chapter 44 of In Cataract Surgery Techniques Complications andManagement. 2^(nd) ed (see complete cite above).

What is needed are ophthalmic methods, techniques and apparatus toadvance the standard of care of cataract and other ophthalmicpathologies.

SUMMARY OF THE INVENTION

The techniques and system disclosed herein provide many advantages.Specifically, rapid and precise openings in the lens capsule andfragmentation of the lens nucleus and cortex is enabled using3-dimensional patterned laser cutting. The duration of the procedure andthe risk associated with opening the capsule and fragmentation of thehard nucleus are reduce, while increasing precision of the procedure.The removal of a lens dissected into small segments is performed using apatterned laser scanning and just a thin aspiration needle. The removalof a lens dissected into small segments is performed using patternedlaser scanning and using a ultrasonic emulsifier with a conventionalphacoemulsification technique or a technique modified to recognize thata segmented lens will likely be more easily removed (i.e., requiringless surgical precision or dexterity) and/or at least with markedreduction in ultrasonic emulsification power, precision and/or duration.There are surgical approaches that enable the formation of very smalland geometrically precise opening(s) in precise locations on the lenscapsule, where the openings in the lens capsule would be very difficultif not impossible to form using conventional, purely manual techniques.The openings enable greater precision or modifications to conventionalophthalmic procedures as well as enable new procedures. For example, thetechniques described herein may be used to facilitate anterior and/orposterior lens removal, implantation of injectable or small foldableIOLs as well as injection of compounds or structures suited to theformation of accommodating IOLs.

Another procedure enabled by the techniques described herein providesfor the controlled formation of a hemi-circular or curvilinear flap inthe anterior lens surface. Contrast to conventional procedures whichrequire a complete circle or nearly complete circular cut. Openingsformed using conventional, manual capsulorhexis techniques relyprimarily on the mechanical shearing properties of lens capsule tissueand uncontrollable tears of the lens capsule to form openings. Theseconventional techniques are confined to the central lens portion or toareas accessible using mechanical cutting instruments and to varyinglimited degrees utilize precise anatomical measurements during theformation of the tears. In contrast, the controllable, patterned lasertechniques described herein may be used to create a semi-circularcapsular flap in virtually any position on the anterior lens surface andin virtually any shape. They may be able to seal spontaneously or withan autologous or synthetic tissue glue or other method. Moreover, thecontrollable, patterned laser techniques described herein also haveavailable and/or utilize precise lens capsule size, measurement andother dimensional information that allows the flap or opening formationwhile minimizing impact on surrounding tissue. The flap is not limitedonly to semi-circular but may be any shape that is conducive to followon procedures such as, for example, injection or formation of complex oradvanced IOL devices or so called injectable polymeric or fixedaccommodating IOLs.

The techniques disclosed herein may be used during cataract surgery toremove all or a part of the anterior capsule, and may be used insituations where the posterior capsule may need to be removedintraoperatively, for example, in special circumstances such as inchildren, or when there is a dense posterior capsular opacity which cannot be removed by suction after the nucleus has been removed. In thefirst, second and third years after cataract surgery, secondaryopacification of the posterior lens capsule is common and is benefitedby a posterior capsulotomy which may be performed or improved utilizingaspects of the techniques disclosed herein.

Because of the precision and atraumatic nature of incisions formed usingthe techniques herein, it is believed that new meaning is brought tominimally invasive ophthalmic surgery and lens incisions that may beself healing.

In one aspect, a method of making an incision in eye tissue includesgenerating a beam of light, focusing the beam at a first focal pointlocated at a first depth in the eye tissue, scanning the beam in apattern on the eye while focused at the first depth, focusing the beamat a second focal point located at a second depth in the eye tissuedifferent than the first depth, and scanning the beam in the pattern onthe eye while focused at the second depth.

In another aspect, a method of making an incision in eye tissue includesgenerating a beam of light, and passing the beam through a multi-focallength optical element so that a first portion of the beam is focused ata first focal point located at a first depth in the eye tissue and asecond portion of the beam is focused at a second focal point located ata second depth in the eye tissue different than first depth.

In yet another aspect, a method of making an incision in eye tissueincludes generating a beam of light having at least a first pulse oflight and a second pulse of light, and focusing the first and secondpulses of light consecutively into the eye tissue, wherein the firstpulse creates a plasma at a first depth within the eye tissue, andwherein the second pulse arrives before the plasma disappears and isabsorbed by the plasma to extend the plasma in the eye tissue along thebeam.

In yet one more aspect, a method of making an incision in eye tissueincludes generating a beam of light, and focusing the light into the eyetissue to create an elongated column of focused light within the eyetissue, wherein the focusing includes subjecting the light to at leastone of a non-spherical lens, a highly focused lens with sphericalaberrations, a curved mirror, a cylindrical lens, an adaptive opticalelement, a prism, and a diffractive optical element.

In another aspect, a method of removing a lens and debris from an eyeincludes generating a beam of light, focusing the light into the eye tofragment the lens into pieces, removing the pieces of lens, and thenfocusing the light into the eye to ablate debris in the eye.

In one more aspect, a method of removing a lens from a lens capsule inan eye includes generating a beam of light, focusing the light into theeye to form incisions in the lens capsule, inserting an ultrasonic probethrough the incision and into the lens capsule to break the lens intopieces, removing the lens pieces from the lens capsule, rinsing the lenscapsule to remove endothermial cells therefrom, and inserting at leastone of a synthetic, foldable intraocular lens or an opticallytransparent gel into the lens capsule.

In another aspect, an ophthalmic surgical system for treating eye tissueincludes a light source for generating a beam of light, a deliverysystem for focusing the beam onto the eye tissue, a controller forcontrolling the light source and the delivery system such that the lightbeam is focused at multiple focal points in the eye tissue at multipledepths within the eye tissue.

In yet another aspect, an ophthalmic surgical system for treating eyetissue includes a light source for generating a beam of light having atleast a first pulse of light and a second pulse of light, a deliverysystem for focusing the beam onto the eye tissue, a controller forcontrolling the light source and the delivery system such that the firstand second pulses of light are consecutively focused onto the eyetissue, wherein the first pulse creates a plasma at a first depth withinthe eye tissue, and wherein the second pulse is arrives before theplasma disappears and absorbed by the plasma to extend the plasma in theeye tissue along the beam.

In one more aspect, an ophthalmic surgical system for treating eyetissue includes a light source for generating a beam of light, adelivery system for focusing the beam onto the eye tissue, the deliverysystem including at least one of a non-spherical lens, a highly focusedlens with spherical aberrations, a curved mirror, a cylindrical lens, anadaptive optical element, a prism, and a diffractive optical element,and a controller for controlling the light source and the deliverysystem such that an elongated column of focused light within the eyetissue is created.

Other objects and features of the present invention will become apparentby a review of the specification, claims and appended figures.

INCORPORATION BY REFERENCE

All publications, patents, and patent applications mentioned in thisspecification are herein incorporated by reference to the same extent asif each individual publication, patent, or patent application wasspecifically and individually indicated to be incorporated by reference.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features of the invention are set forth with particularity inthe appended claims. A better understanding of the features andadvantages of the present invention will be obtained by reference to thefollowing detailed description that sets forth illustrative embodiments,in which the principles of the invention are utilized, and theaccompanying drawings of which:

FIG. 1 is a plan diagram of a system that projects or scans an opticalbeam into a patient's eye.

FIG. 2 is a diagram of the anterior chamber of the eye and the laserbeam producing plasma at the focal point on the lens capsule.

FIG. 3 is a planar view of the iris and lens with a circular pattern forthe anterior capsulotomy (capsulorexis).

FIG. 4 is a diagram of the line pattern applied across the lens for OCTmeasurement of the axial profile of the anterior chamber.

FIG. 5 is a diagram of the anterior chamber of the eye and the3-dimensional laser pattern applied across the lens capsule.

FIG. 6 is an axially-elongated plasma column produced in the focal zoneby sequential application of a burst of pulses (1, 2, and 3) with adelay shorter than the plasma life time.

FIGS. 7A-7B are multi-segmented lenses for focusing the laser beam into3 points along the same axis.

FIGS. 7C-7D are multi-segmented lenses with co-axial and off-axialsegments having focal points along the same axis but different focaldistances F1, F2, F3.

FIG. 8 is an axial array of fibers (1,2,3) focused with a set of lensesinto multiple points (1,2,3) and thus producing plasma at differentdepths inside the tissue (1,2,3).

FIG. 9A and FIG. 9B are diagrams illustrating examples of the patternsthat can be applied for nucleus segmentation.

FIGS. 10A-10C are planar views of some of the combined patterns forsegmented capsulotomy and phaco-fragmentation.

FIG. 11 is a plan diagram of one system embodiment that projects orscans an optical beam into a patient's eye.

FIG. 12 is a plan diagram of another system embodiment that projects orscans an optical beam into a patient's eye.

FIG. 13 is a plan diagram of yet another system embodiment that projectsor scans an optical beam into a patient's eye.

FIG. 14 is a flow diagram showing the steps utilized in a “track andtreat” approach to material removal.

FIG. 15 is a flow diagram showing the steps utilized in a “track andtreat” approach to material removal that employs user input.

FIG. 16 is a perspective view of a transverse focal zone created by ananamorphic optical scheme.

FIGS. 17A-17C are perspective views of an anamorphic telescopeconfiguration for constructing an inverted Keplerian telescope.

FIG. 18 is a side view of prisms used to extend the beam along a singlemeridian.

FIG. 19 is a top view illustrating the position and motion of atransverse focal volume on the eye lens.

FIG. 20 illustrates fragmentation patterns of an ocular lens produced byone embodiment of the present invention.

FIG. 21 illustrates circular incisions of an ocular lens produced by oneembodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention can be implemented by a system that projects orscans an optical beam into a patient's eye 1, such as the system shownin FIG. 1. The system includes a light source 10 (e.g. laser, laserdiode, etc.), which may be controlled by control electronics 12, via aninput and output device 14, to create optical beam 11 (either cw orpulsed). Control electronics 12 may be a computer, microcontroller, etc.Scanning may be achieved by using one or more moveable optical elements(e.g. lenses, gratings, or as shown in FIG. 1 a mirror(s) 16) which alsomay be controlled by control electronics 12, via input and output device14. Mirror 16 may be tilted to deviate the optical beam 11 as shown inFIG. 1, and direct beam 11 towards the patient's eye 1. An optionalophthalmic lens 18 can be used to focus the optical beam 11 into thepatient's eye 1. The positioning and character of optical beam 11 and/orthe scan pattern it forms on the eye may be further controlled by use ofan input device 20 such as a joystick, or any other appropriate userinput device.

Techniques herein include utilizing a light source 10 such as a surgicallaser configured to provide one or more of the following parameters:

1) pulse energy up to 1 μJ repetition rate up to 1 MHz, pulse duration<1 ps

2) pulse energy up to 10 μJ rep. rate up to 100 kHz, pulse duration <1ps.

3) Pulse energy up to 1000 μJ, rep rate up to 1 kHz, pulse duration <3ps.

Additionally, the laser may use wavelengths in a variety of rangesincluding in the near-infrared range: 800-1100 nm. In one aspect,near-infrared wavelengths are selected because tissue absorption andscattering is reduced. Additionally, a laser can be configured toprovide low energy ultrashort pulses of near-infrared radiation withpulse durations below 10 ps or below 1 ps, alone or in combination withpulse energy not exceeding 100 μJ, at high repetition rate includingrates above 1 kHz, and above 10 kHz.

Short pulsed laser light focused into eye tissue 2 will producedielectric breakdown at the focal point, rupturing the tissue 2 in thevicinity of the photo-induced plasma (see FIG. 2). The diameter d of thefocal point is given by d=λF/D_(b), where F is the focal length of thelast focusing element, D_(b) is the beam diameter on the last lens, andλ is the wavelength. For a focal length F=160 mm, beam diameter on thelast lens D_(b)=10 mm, and wavelength λ=1.04 um, the focal spot diameterwill be d≈λ/(2·NA)≈λF/D_(b)=15 μm, where the numerical aperture of thefocusing optics, NA≈D_(b)/(2F).

To provide for continuous cutting, the laser spots should not beseparated by more than a width of the crater produced by the laser pulsein tissue. Assuming the rupture zone being R=15 μm (at low energiesionization might occur in the center of the laser spot and not expand tothe full spot size), and assuming the maximal diameter of thecapsulotomy circle being D_(c)=8 mm, the number of required pulses willbe: N=πD_(c)/R=1675 to provide a circular cut line 22 around thecircumference of the eye lens 3 as illustrated in FIG. 3. For smallerdiameters ranging from 5-7 mm, the required number of pulses would beless. If the rupture zone were larger (e.g. 50 μm), the number of pulseswould drop to N=503.

To produce an accurate circular cut, these pulses should be delivered totissue over a short eye fixation time. Assuming the fixation time t=0.2s, laser repetition rate should be: r=N/t=8.4 kHz. If the fixation timewere longer, e.g. 0.5 s, the required rep. rate could be reduced to 3.4kHz. With a rupture zone of 50 μm the rep. rate could further drop to 1kHz.

Threshold radiant exposure of the dielectric breakdown with 4 ns pulsesis about Φ=100 J/cm². With a focal spot diameter being d=15 thethreshold pulse energy will be E_(th)=Φ*πd²/4=176 μJ. For stable andreproducible operation, pulse energy should exceed the threshold by atleast a factor of 2, so pulse energy of the target should be E=352 μJ.The creation of a cavitation bubble might take up to 10% of the pulseenergy, i.e. E_(b)=35 μJ. This corresponds to a bubble diameter

$\begin{matrix}{d_{b} = \sqrt[3]{\frac{6E_{b}}{\pi \; P_{a}}}} \\{= {48{{µm}.}}}\end{matrix}$

The energy level can be adjusted to avoid damage to the cornealendothelium. As such, the threshold energy of the dielectric breakdowncould be minimized by reducing the pulse duration, for example, in therange of approximately 0.1-1 ps. Threshold radiant exposure, Φ, fordielectric breakdown for 100 fs is about Φ=2 J/cm²; for 1 ps it is Φ=2.5J/cm². Using the above pulse durations, and a focal spot diameter d=15the threshold pulse energies will be E_(th)=Φ*πd²/4=3.5 and 4.4 μJ for100 fs and 1 ps pulses, respectively. The pulse energy could instead beselected to be a multiple of the threshold energy, for example, at leasta factor of 2. If a factor of 2 is used, the pulse energies on thetarget would be E_(th)=7 and 9 μJ, respectively. These are only twoexamples. Other pulse energy duration times, focal spot sizes andthreshold energy levels are possible and are within the scope of thepresent invention.

A high repetition rate and low pulse energy can be utilized for tighterfocusing of the laser beam. In one specific example, a focal distance ofF=50 mm is used while the beam diameter remains D_(b)=10 mm, to providefocusing into a spot of about 4 μm in diameter. Aspherical optics canalso be utilized. An 8 mm diameter opening can be completed in a time of0.2 s using a repetition rate of about 32 kHz.

The laser 10 and controller 12 can be set to locate the surface of thecapsule and ensure that the beam will be focused on the lens capsule atall points of the desired opening. Imaging modalities and techniquesdescribed herein, such as for example, Optical Coherence Tomography(OCT) or ultrasound, may be used to determine the location and measurethe thickness of the lens and lens capsule to provide greater precisionto the laser focusing methods, including 2D and 3D patterning. Laserfocusing may also be accomplished using one or more methods includingdirect observation of an aiming beam, Optical Coherence Tomography(OCT), ultrasound, or other known ophthalmic or medical imagingmodalities and combinations thereof.

As shown in FIG. 4, OCT imaging of the anterior chamber can be performedalong a simple linear scan 24 across the lens using the same laserand/or the same scanner used to produce the patterns for cutting. Thisscan will provide information about the axial location of the anteriorand posterior lens capsule, the boundaries of the cataract nucleus, aswell as the depth of the anterior chamber. This information may then beloaded into the laser 3-D scanning system, and used to program andcontrol the subsequent laser assisted surgical procedure. Theinformation may be used to determine a wide variety of parametersrelated to the procedure such as, for example, the upper and lower axiallimits of the focal planes for cutting the lens capsule and segmentationof the lens cortex and nucleus, the thickness of the lens capsule amongothers. The imaging data may be averaged across a 3-line pattern asshown in FIG. 9.

An example of the results of such a system on an actual humancrystalline lens is shown in FIG. 20. A beam of 10 μJ, 1 ps pulsesdelivered at a pulse repetition rate of 50 kHz from a laser operating ata wavelength of 1045 nm was focused at NA=0.05 and scanned from thebottom up in a pattern of 4 circles in 8 axial steps. This produced thefragmentation pattern in the ocular lens shown in FIG. 20. FIG. 21 showsin detail the resultant circular incisions, which measured ˜10 μm indiameter, and ˜100 μm in length.

FIG. 2 illustrates an exemplary illustration of the delineationavailable using the techniques described herein to anatomically definethe lens. As can be seen in FIG. 2, the capsule boundaries andthickness, the cortex, epinucleus and nucleus are determinable. It isbelieved that OCT imaging may be used to define the boundaries of thenucleus, cortex and other structures in the lens including, for example,the thickness of the lens capsule including all or a portion of theanterior or posterior capsule. In the most general sense, one aspect ofthe present invention is the use of ocular imaging data obtained asdescribed herein as an input into a laser scanning and/or patterntreatment algorithm or technique that is used to as a guide in theapplication of laser energy in novel laser assisted ophthalmicprocedures. In fact, the imaging and treatment can be performed usingthe same laser and the same scanner. While described for use withlasers, other energy modalities may also be utilized.

It is to be appreciated that plasma formation occurs at the waist of thebeam. The axial extent of the cutting zone is determined by thehalf-length L of the laser beam waist, which can be expressed as:L−λ/(4·NA²)=dF/D_(b). Thus the lower the NA of the focusing optics, thelonger waist of the focused beam, and thus a longer fragmentation zonecan be produced. For F=160 mm, beam diameter on the last lens D_(b)=10mm, and focal spot diameter d=15 μm, the laser beam waist half-length Lwould be 240 μm.

With reference to FIG. 5, a three dimensional application of laserenergy 26 can be applied across the capsule along the pattern producedby the laser-induced dielectric breakdown in a number of ways such as,for example:

1) Producing several circular or other pattern scans consecutively atdifferent depths with a step equal to the axial length of the rupturezone. Thus, the depth of the focal point (waist) in the tissue isstepped up or down with each consecutive scan. The laser pulses aresequentially applied to the same lateral pattern at different depths oftissue using, for example, axial scanning of the focusing elements oradjusting the optical power of the focusing element while, optionally,simultaneously or sequentially scanning the lateral pattern. The adverseresult of laser beam scattering on bubbles, cracks and/or tissuefragments prior to reaching the focal point can be avoided by firstproducing the pattern/focusing on the maximal required depth in tissueand then, in later passes, focusing on more shallow tissue spaces. Notonly does this “bottom up” treatment technique reduce unwanted beamattenuation in tissue above the target tissue layer, but it also helpsprotect tissue underneath the target tissue layer. By scattering thelaser radiation transmitted beyond the focal point on gas bubbles,cracks and/or tissue fragments which were produced by the previousscans, these defects help protect the underlying retina. Similarly, whensegmenting a lens, the laser can be focused on the most posteriorportion of the lens and then moved more anteriorly as the procedurecontinues.

2) Producing axially-elongated rupture zones at fixed points by:

a) Using a sequence of 2-3 pulses in each spot separated by a few ps.Each pulse will be absorbed by the plasma 28 produced by the previouspulse and thus will extend the plasma 28 upwards along the beam asillustrated in FIG. 6A. In this approach, the laser energy should be 2or 3 times higher, i.e. 20-30 μJ. Delay between the consecutive pulsesshould be longer than the plasma formation time (on the order of 0.1 ps)but not exceed the plasma recombination time (on the order ofnanoseconds)

b) Producing an axial sequence of pulses with slightly differentfocusing points using multiple co-axial beams with differentpre-focusing or multifocal optical elements. This can be achieved byusing multi-focal optical elements (lenses, mirrors, diffractive optics,etc.). For example, a multi-segmented lens 30 can be used to focus thebeam into multiple points (e.g. three separate points) along the sameaxis, using for example co-axial (see FIGS. 7A-7C) or off-coaxial (seeFIG. 7D) segments to produce varying focal lengths (e.g. F₁, F₂, F₃).The multi-focal element 30 can be co-axial, or off-axis-segmented, ordiffractive. Co-axial elements may have more axially-symmetric focalpoints, but will have different sizes due to the differences in beamdiameters in each segment. Off-axial elements might have less symmetricfocal points but all the elements can produce the foci of the samesizes.

c) Producing an elongated focusing column (as opposed to just a discretenumber of focal points) using: (1) non-spherical (aspherical) optics, or(2) utilizing spherical aberrations in a lens with a high F number, or(3) diffractive optical element (hologram).

d) Producing an elongated zone of ionization using multiple opticalfibers. For example, an array of optical fibers 32 of different lengthscan be imaged with a set of lenses 34 into multiple focal points atdifferent depths inside the tissue as shown in FIG. 8.

Patterns of Scanning:

For anterior and posterior capsulotomy, the scanning patterns can becircular and spiral, with a vertical step similar to the length of therupture zone. For segmentation of the eye lens 3, the patterns can belinear, planar, radial, radial segments, circular, spiral, curvilinearand combinations thereof including patterning in two and/or threedimensions. Scans can be continuous straight or curved lines, or one ormore overlapping or spaced apart spots and/or line segments. Severalscan patterns 36 are illustrated in FIGS. 9A and 9B, and combinations ofscan patterns 38 are illustrated in FIGS. 10A-10C. Beam scanning withthe multifocal focusing and/or patterning systems is particularlyadvantageous to successful lens segmentation since the lens thickness ismuch larger than the length of the beam waist axial. In addition, theseand other 2D and 3D patterns may be used in combination with OCT toobtain additional imaging, anatomical structure or make-up (i.e., tissuedensity) or other dimensional information about the eye including butnot limited to the lens, the cornea, the retina and as well as otherportions of the eye.

The exemplary patterns allow for dissection of the lens cortex andnucleus into fragments of such dimensions that they can be removedsimply with an aspiration needle, and can be used alone to performcapsulotomy. Alternatively, the laser patterning may be used topre-fragment or segment the nucleus for later conventional ultrasonicphacoemulsification. In this case however, the conventionalphacoemulsification would be less than a typical phacoemulsificationperformed in the absence of the inventive segmenting techniques becausethe lens has been segmented. As such, the phacoemulsification procedurewould likely require less ultrasonic energy to be applied to the eye,allowing for a shortened procedure or requiring less surgical dexterity.

Complications due to the eye movements during surgery can be reduced oreliminated by performing the patterned laser cutting very rapidly (e.g.within a time period that is less than the natural eye fixation time).Depending on the laser power and repetition rate, the patterned cuttingcan be completed between 5 and 0.5 seconds (or even less), using a laserrepetition rate exceeding 1 kHz.

The techniques described herein may be used to perform new ophthalmicprocedures or improve existing procedures, including anterior andposterior capsulotomy, lens fragmentation and softening, dissection oftissue in the posterior pole (floaters, membranes, retina), as well asincisions in other areas of the eye such as, but not limited to, thesclera and iris.

Damage to an IOL during posterior capsulotomy can be reduced orminimized by advantageously utilizing a laser pattern initially focusedbeyond the posterior pole and then gradually moved anteriorly undervisual control by the surgeon alone or in combination with imaging dataacquired using the techniques described herein.

For proper alignment of the treatment beam pattern, an alignment beamand/or pattern can be first projected onto the target tissue withvisible light (indicating where the treatment pattern will be projected.This allows the surgeon to adjust the size, location and shape of thetreatment pattern. Thereafter, the treatment pattern can be rapidlyapplied to the target tissue using an automated 3 dimensional patterngenerator (in the control electronics 12) by a short pulsed cuttinglaser having high repetition rate.

In addition, and in particular for capsulotomy and nuclearfragmentation, an automated method employing an imaging modality can beused, such as for example, electro-optical, OCT, acoustic, ultrasound orother measurement, to first ascertain the maximum and minimum depths ofcutting as well as the size and optical density of the cataract nucleus.Such techniques allow the surgeon account for individual differences inlens thickness and hardness, and help determine the optimal cuttingcontours in patients. The system for measuring dimensions of theanterior chamber using OCT along a line, and/or pattern (2D or 3D orothers as described herein) can be integrally the same as the scanningsystem used to control the laser during the procedure. As such, the dataincluding, for example, the upper and lower boundaries of cutting, aswell as the size and location of the nucleus, can be loaded into thescanning system to automatically determine the parameters of the cutting(i.e., segmenting or fracturing) pattern. Additionally, automaticmeasurement (using an optical, electro-optical, acoustic, or OCT device,or some combination of the above) of the absolute and relative positionsand/or dimensions of a structure in the eye (e.g. the anterior andposterior lens capsules, intervening nucleus and lens cortex) forprecise cutting, segmenting or fracturing only the desired tissues (e.g.lens nucleus, tissue containing cataracts, etc.) while minimizing oravoiding damage to the surrounding tissue can be made for current and/orfuture surgical procedures. Additionally, the same ultrashort pulsedlaser can be used for imaging at a low pulse energy, and then forsurgery at a high pulse energy.

The use of an imaging device to guide the treatment beam may be achievedmany ways, such as those mentioned above as well as additional examplesexplained next (which all function to characterize tissue, and continueprocessing it until a target is removed). For example, in FIG. 11, alaser source LS and (optional) aiming beam source AIM have outputs thatare combined using mirror DM1 (e.g. dichroic mirror). In thisconfiguration, laser source LS may be used for both therapeutics anddiagnostics. This is accomplished by means of mirror M1 which serves toprovide both reference input R and sample input S to an OCTInterferometer by splitting the light beam B (centerlines shown) fromlaser source LS. Because of the inherent sensitivity of OCTInterferometers, mirror M1 may be made to reflect only a small portionof the delivered light. Alternatively, a scheme employing polarizationsensitive pickoff mirrors may be used in conjunction with a quarter waveplate (not shown) to increase the overall optical efficiency of thesystem. Lens L1 may be a single element or a group of elements used toadjust the ultimate size or location along the z-axis of the beam Bdisposed to the target at point P. When used in conjunction withscanning in the X & Y axes, this configuration enables 3-dimensionalscanning and/or variable spot diameters (i.e. by moving the focal pointof the light along the z-axis).

In this example, transverse (XY) scanning is achieved by using a pair oforthogonal galvanometric mirrors G1 & G2 which may provide 2-dimensionalrandom access scanning of the target. It should be noted that scanningmay be achieved in a variety of ways, such as moving mirror M2, spinningpolygons, translating lenses or curved mirrors, spinning wedges, etc.and that the use of galvanometric scanners does not limit the scope ofthe overall design. After leaving the scanner, light encounters lens L2which serves to focus the light onto the target at point P inside thepatient's eye EYE. An optional ophthalmic lens OL may be used to helpfocus the light. Ophthalmic lens OL may be a contact lens and furtherserve to dampen any motion of eye EYE, allowing for more stabletreatment. Lens L2 may be made to move along the z-axis in coordinationwith the rest of the optical system to provide for 3-dimensionalscanning, both for therapy and diagnosis. In the configuration shown,lens L2 ideally is moved along with the scanner G1 & G2 to maintaintelecentricity. With that in mind, one may move the entire opticalassembly to adjust the depth along the z-axis. If used with ophthalmiclens OL, the working distance may be precisely held. A device such asthe Thorlabs EAS504 precision stepper motor can be used to provide boththe length of travel as well as the requisite accuracy and precision toreliably image and treat at clinically meaningful resolutions. As shownit creates a telecentric scan, but need not be limited to such a design.

Mirror M2 serves to direct the light onto the target, and may be used ina variety of ways. Mirror M2 could be a dichroic element that the userlooks through in order to visualize the target directly or using acamera, or may be made as small as possible to provide an opportunityfor the user to view around it, perhaps with a binocular microscope. Ifa dichroic element is used, it may be made to be photopically neutral toavoid hindering the user's view. An apparatus for visualizing the targettissue is shown schematically as element V, and is preferably a camerawith an optional light source for creating an image of the targettissue. The optional aiming beam AIM may then provide the user with aview of the disposition of the treatment beam, or the location of theidentified targets. To display the target only, AIM may be pulsed onwhen the scanner has positioned it over an area deemed to be a target.The output of visualization apparatus V may be brought back to thesystem via the input/output device IO and displayed on a screen, such asa graphical user interface GUI. In this example, the entire system iscontrolled by the controller CPU, and data moved through input/outputdevice IO. Graphical user interface GUI may be used to process userinput, and display the images gathered by both visualization apparatus Vand the OCT interferometer. There are many possibilities for theconfiguration of the OCT interferometer, including time and frequencydomain approaches, single and dual beam methods, etc, as described inU.S. Pat. Nos. 5,748,898; 5,748,352; 5,459,570; 6,111,645; and 6,053,613(which are incorporated herein by reference.

Information about the lateral and axial extent of the cataract andlocalization of the boundaries of the lens capsule will then be used fordetermination of the optimal scanning pattern, focusing scheme, andlaser parameters for the fragmentation procedure. Much if not all ofthis information can be obtained from visualization of the targettissue. For example, the axial extent of the fragmentation zone of asingle pulse should not exceed the distance between (a) the cataract andthe posterior capsule, and (b) the anterior capsule and the cornealendothelium. In the cases of a shallow anterior chamber and/or a largecataract, a shorter fragmentation zone should be selected, and thus morescanning planes will be required. Conversely, for a deep anteriorchamber and/or a larger separation between the cataract and theposterior capsule a longer fragmentation zone can be used, and thus lessplanes of scanning will be required. For this purpose an appropriatefocusing element will be selected from an available set. Selection ofthe optical element will determine the width of the fragmentation zone,which in turn will determine the spacing between the consecutive pulses.This, in turn, will determine the ratio between the scanning rate andrepetition rate of the laser pulses. In addition, the shape of thecataract will determine the boundaries of the fragmentation zone andthus the optimal pattern of the scanner including the axial and lateralextent of the fragmentation zone, the ultimate shape of the scan, numberof planes of scanning, etc.

FIG. 12 shows an alternate embodiment in which the imaging and treatmentsources are different. A dichroic mirror DM2 has been added to theconfiguration of FIG. 11 to combine the imaging and treatment light, andmirror M1 has been replaced by beam splitter BS which is highlytransmissive at the treatment wavelength, but efficiently separates thelight from the imaging source SLD for use in the OCT Interferometer.Imaging source SLD may be a superluminescent diode having a spectraloutput that is nominally 50 nm wide, and centered on or around 835 nm,such as the SuperLum SLD-37. Such a light source is well matched to theclinical application, and sufficiently spectrally distinct from thetreatment source, thus allowing for elements DM and BS to be reliablyfabricated without the necessarily complicated and expensive opticalcoatings that would be required if the imaging and treatment sourceswere closer in wavelength.

FIG. 13 shows an alternate embodiment incorporating a confocalmicroscope CM for use as an imaging system. In this configuration,mirror M1 reflects a portion of the backscattered light from beam B intolens L3. Lens L3 serves to focus this light through aperture A (servingas a spatial filter) and ultimately onto detector D. As such, aperture Aand point P are optically conjugate, and the signal received by detectorD is quite specific when aperture A is made small enough to rejectsubstantially the entire background signal. This signal may thus be usedfor imaging, as is known in the art. Furthermore, a fluorophore may beintroduced into the target to allow for specific marking of eithertarget or healthy tissue. In this approach, the ultrafast laser may beused to pump the absorption band of the fluorophore via a multiphotonprocess or an alternate source (not shown) could be used in a mannersimilar to that of FIG. 12.

FIG. 14 is a flowchart outlining the steps utilized in a “track andtreat” approach to material removal. First an image is created byscanning from point to point, and potential targets identified. When thetreatment beam is disposed over a target, the system can transmit thetreatment beam, and begin therapy. The system may move constantlytreating as it goes, or dwell in a specific location until the target isfully treated before moving to the next point.

The system operation of FIG. 14 could be modified to incorporate userinput. As shown in FIG. 15, a complete image is displayed to the user,allowing them to identify the target(s). Once identified, the system canregister subsequent images, thus tracking the user defined target(s).Such a registration scheme may be implemented in many different ways,such as by use of the well known and computationally efficient Sobel orCanny edge detection schemes. Alternatively, one or more readilydiscernable marks may be made in the target tissue using the treatmentlaser to create a fiduciary reference without patient risk (since thetarget tissue is destined for removal).

In contrast to conventional laser techniques, the above techniquesprovide (a) application of laser energy in a pattern, (b) a highrepetition rate so as to complete the pattern within the natural eyefixation time, (c) application of sub-ps pulses to reduce the thresholdenergy, and (d) the ability to integrate imaging and treatment for anautomated procedure.

Laser Delivery System

The laser delivery system in FIG. 1 can be varied in several ways. Forexample, the laser source could be provided onto a surgical microscope,and the microscope's optics used by the surgeon to apply the laserlight, perhaps through the use of a provided console. Alternately, thelaser and delivery system would be separate from the surgical microscopeand would have an optical system for aligning the aiming beam forcutting. Such a system could swing into position using an articulatingarm attached to a console containing the laser at the beginning of thesurgery, and then swing away allowing the surgical microscope to swinginto position.

The pattern to be applied can be selected from a collection of patternsin the control electronics 12, produced by the visible aiming beam, thenaligned by the surgeon onto the target tissue, and the patternparameters (including for example, size, number of planar or axialelements, etc.) adjusted as necessary for the size of the surgical fieldof the particular patient (level of pupil dilation, size of the eye,etc.). Thereafter, the system calculates the number of pulses thatshould be applied based on the size of the pattern. When the patterncalculations are complete, the laser treatment may be initiated by theuser (i.e., press a pedal) for a rapid application of the pattern with asurgical laser.

The laser system can automatically calculate the number of pulsesrequired for producing a certain pattern based on the actual lateralsize of the pattern selected by surgeon. This can be performed with theunderstanding that the rupture zone by the single pulse is fixed(determined by the pulse energy and configuration of the focusingoptics), so the number of pulses required for cutting a certain segmentis determined as the length of that segment divided by the width of therupture zone by each pulse. The scanning rate can be linked to therepetition rate of the laser to provide a pulse spacing on tissuedetermined by the desired distance. The axial step of the scanningpattern will be determined by the length of the rupture zone, which isset by the pulse energy and the configuration of the focusing optics.

Fixation Considerations

The methods and systems described herein can be used alone or incombination with an aplanatic lens (as described in, for example, theU.S. Pat. No. 6,254,595 patent, incorporated herein by reference) orother device to configure the shape of the cornea to assist in the lasermethods described herein. A ring, forceps or other securing means may beused to fixate the eye when the procedure exceeds the normal fixationtime of the eye. Regardless whether an eye fixation device is used,patterning and segmenting methods described herein may be furthersubdivided into periods of a duration that may be performed within thenatural eye fixation time.

Another potential complication associated with a dense cutting patternof the lens cortex is the duration of treatment: If a volume of 6×6×4mm=144 mm³ of lens is segmented, it will require N=722,000 pulses. Ifdelivered at 50 kHz, it will take 15 seconds, and if delivered at 10 kHzit will take 72 seconds. This is much longer than the natural eyefixation time, and it might require some fixation means for the eye.Thus, only the hardened nucleus may be chosen to be segmented to easeits removal. Determination of its boundaries with the OCT diagnosticswill help to minimize the size of the segmented zone and thus the numberof pulses, the level of cumulative heating, and the treatment time. Ifthe segmentation component of the procedure duration exceeds the naturalfixation time, then the eye may be stabilized using a conventional eyefixation device.

Thermal Considerations

In cases where very dense patterns of cutting are needed or desired,excess accumulation of heat in the lens may damage the surroundingtissue. To estimate the maximal heating, assume that the bulk of thelens is cut into cubic pieces of 1 mm in size. If tissue is dissectedwith E₁=10 uJ pulses fragmenting a volume of 15 um in diameter and 200um in length per pulse, then pulses will be applied each 15 um. Thus a1×1 mm plane will require 66×66=4356 pulses. The 2 side walls willrequire 2×66×5=660 pulses, thus total N=5016 pulses will be required percubic mm of tissue. Since all the laser energy deposited during cuttingwill eventually be transformed into heat, the temperature elevation willbe DT=(E₁*N)/pcV=50.16 mJ/(4.19 mJ/K)=12 K. This will lead to maximaltemperature T=37+12° C.=49° C. This heat will dissipate in about oneminute due to heat diffusion. Since peripheral areas of the lens willnot be segmented (to avoid damage to the lens capsule) the averagetemperature at the boundaries of the lens will actually be lower. Forexample, if only half of the lens volume is fragmented, the averagetemperature elevation at the boundaries of the lens will not exceed 6°C. (T=43° C.) and on the retina will not exceed 0.1 C. Such temperatureelevation can be well tolerated by the cells and tissues. However, muchhigher temperatures might be dangerous and should be avoided.

To reduce heating, a pattern of the same width but larger axial lengthcan be formed, so these pieces can still be removed by suction through aneedle. For example, if the lens is cut into pieces of 1×1×4 mm in size,a total of N=6996 pulses will be required per 4 cubic mm of tissue. Thetemperature elevation will be DT=(E₁*N)/pcV=69.96 mJ/(4.19 mJ/K)/4=1.04K. Such temperature elevation can be well tolerated by the cells andtissues.

An alternative solution to thermal limitations can be the reduction ofthe total energy required for segmentation by tighter focusing of thelaser beam. In this regime a higher repetition rate and low pulse energymay be used. For example, a focal distance of F=50 mm and a beamdiameter of D_(b)=10 mm would allow for focusing into a spot of about 4μm in diameter. In this specific example, repetition rate of about 32kHz provides an 8 mm diameter circle in about 0.2 s.

To avoid retinal damage due to explosive vaporization of melanosomesfollowing absorption of the short laser pulse the laser radiant exposureon the RPE should not exceed 100 mJ/cm². Thus NA of the focusing opticsshould be adjusted such that laser radiant exposure on the retina willnot exceed this safety limit. With a pulse energy of 10 μJ, the spotsize on retina should be larger than 0.1 mm in diameter, and with a 1 mJpulse it should not be smaller than 1 mm. Assuming a distance of 20 mmbetween lens and retina, these values correspond to minimum numericalapertures of 0.0025 and 0.025, respectively.

To avoid thermal damage to the retina due to heat accumulation duringthe lens fragmentation the laser irradiance on the retina should notexceed the thermal safety limit for near-IR radiation—on the order of0.6 W/cm². With a retinal zone of about 10 mm in diameter (8 mm patternsize on a lens+1 mm on the edges due to divergence) it corresponds tototal power of 0.5 W on the retina.

Transverse Focal Volume

It is also possible to create a transverse focal volume 50 instead of anaxial focal volume described above. An anamorphic optical scheme mayused to produce a focal zone 39 that is a “line” rather than a singlepoint, as is typical with spherically symmetric elements (see FIG. 16).As is standard in the field of optical design, the term “anamorphic” ismeant herein to describe any system which has different equivalent focallengths in each meridian. It should be noted that any focal point has adiscrete depth of field. However, for tightly focused beams, such asthose required to achieve the electric field strength sufficient todisrupt biological material with ultrashort pulses (defined ast_(pulse)<10 ps), the depth of focus is proportionally short.

Such a 1-dimensional focus may be created using cylindrical lenses,and/or mirrors. An adaptive optic may also be used, such as a MEMSmirror or a phased array. When using a phased array, however, carefulattention should be paid to the chromatic effects of such a diffractivedevice. FIGS. 17A-17C illustrate an anamorphic telescope configuration,where cylindrical optics 40 a/b and spherical lens 42 are used toconstruct an inverted Keplerian telescope along a single meridian (seeFIG. 17A) thus providing an elongated focal volume transverse to theoptical axis (see FIG. 17C). Compound lenses may be used to allow thebeam's final dimensions to be adjustable.

FIG. 18 shows the use of a pair of prisms 46 a/b to extend the beamalong a single meridian, shown as CA. In this example, CA is reducedrather than enlarged to create a linear focal volume.

The focus may also be scanned to ultimately produce patterns. To effectaxial changes, the final lens may be made to move along the system'sz-axis to translate the focus into the tissue. Likewise, the final lensmay be compound, and made to be adjustable. The 1-dimensional focus mayalso be rotated, thus allowing it to be aligned to produce a variety ofpatterns, such as those shown in FIGS. 9 and 10. Rotation may beachieved by rotating the cylindrical element itself. Of course, morethan a single element may be used. The focus may also be rotated byusing an additional element, such as a Dove prism (not shown). If anadaptive optic is used, rotation may be achieved by rewriting thedevice, thus streamlining the system design by eliminating a movingpart.

The use of a transverse line focus allows one to dissect a cataractouslens by ablating from the posterior to the anterior portion of the lens,thus planing it. Furthermore, the linear focus may also be used toquickly open the lens capsule, readying it for extraction. It may alsobe used for any other ocular incision, such as the conjunctiva, etc.(see FIG. 19).

Cataract Removal Using a Track and Treat Approach

A “track and treat” approach is one that integrates the imaging andtreatment aspect of optical eye surgery, for providing an automatedapproach to removal of debris such as cataractous and cellular materialprior to the insertion of an IOL. An ultrafast laser is used to fragmentthe lens into pieces small enough to be removed using anirrigating/aspirating probe of minimal size without necessarilyrupturing the lens capsule. An approach such as this that uses tiny,self-sealing incisions may be used to provide a capsule for filling witha gel or elastomeric IOL. Unlike traditional hard IOLS that requirelarge incisions, a gel or liquid may be used to fill the entire capsule,thus making better use of the body's own accommodative processes. Assuch, this approach not only addresses cataract, but presbyopia as well.

Alternately, the lens capsule can remain intact, where bilateralincisions are made for aspirating tips, irrigating tips, and ultrasoundtips for removing the bulk of the lens. Thereafter, the completecontents of the bag/capsule can be successfully rinsed/washed, whichwill expel the debris that can lead to secondary cataracts. Then, withthe lens capsule intact, a minimal incision is made for either afoldable IOL or optically transparent gel injected through incision tofill the bag/capsule. The gel would act like the natural lens with alarger accommodating range.

It is to be understood that the present invention is not limited to theembodiment(s) described above and illustrated herein, but encompassesany and all variations falling within the scope of the appended claims.For example, materials, processes and numerical examples described aboveare exemplary only, and should not be deemed to limit the claims.Multi-segmented lens 30 can be used to focus the beam simultaneously atmultiple points not axially overlapping (i.e. focusing the beam atmultiple foci located at different lateral locations on the targettissue). Further, as is apparent from the claims and specification, notall method steps need be performed in the exact order illustrated orclaimed, but rather in any order that accomplishes the goals of thesurgical procedure.

DETAILED DESCRIPTION OF THE INVENTION

While preferred embodiments of the present invention have been shown anddescribed herein, it will be obvious to those skilled in the art thatsuch embodiments are provided by way of example only. Numerousvariations, changes, and substitutions will now occur to those skilledin the art without departing from the invention. It should be understoodthat various alternatives to the embodiments of the invention describedherein may be employed in practicing the invention. It is intended thatthe following claims define the scope of the invention and that methodsand structures within the scope of these claims and their equivalents becovered thereby.

1.-20. (canceled)
 21. A method of making an incision in eye tissueduring a cataract surgical procedure, the method comprising: generatinga beam of light, passing the beam of light through a multi-focal lengthoptical element, wherein the multi-focal length optical elementsimultaneously focuses a first portion of the beam of light at a firstfocal point located at a first depth in the eye tissue and a secondportion of the beam of light at a second focal point located at a seconddepth in the eye tissue different than the first depth; and scanning thefirst and second focal points in at least a transverse direction to formthe incision in the eye tissue.
 22. The method of claim 21, wherein themulti-focal length optical element includes lenses, mirrors, ordiffractive optics.
 23. The method of claim 21, wherein the multi-focallength optical element includes a multi-segmented lens having at leasttwo co-axially arranged segments which focus the beam of light into thefirst and second focal points along a same axis.
 24. The method of claim21, wherein the multi-focal length optical element includes amulti-segmented lens having at least two off-coaxially arranged segmentswhich focus the beam of light into the first and second focal pointsalong a same axis.
 25. The method of claim 21, wherein the scanning stepfurther includes changing depths of the first and second focal points.26. The method of claim 25, further comprising: operating an imagingsystem, which is coupled to control electronics, to acquire image datafrom locations distributed throughout a volume of a crystalline lens ofthe eye and construct one or more images of at least a portion of thecrystalline lens from the image data; and identifying, using the controlelectronics, a cutting region based on the image data, the cuttingregion defining an anterior cutting boundary and a posterior cuttingboundary and including a portion of the crystalline lens, wherein theposterior cutting boundary is disposed anterior to the lens posteriorcapsule; wherein the scanning step includes using the controlelectronics to control an optical scanning system based in part on theimage data and a scanning pattern, to scan the first focal point and thesecond focal point within the cutting region.
 27. The method of claim26, wherein the imaging system is an optical coherence tomographysystem.
 28. The method of claim 26, further comprising the controlelectronics receiving input from an operator regarding one or moreparameters of the scanning pattern.
 29. The method of claim 21, whereinthe beam of light is a pulsed laser beam having a pulse repetition ratebetween 1 kHz and 1,000 kHz, and a pulse energy between 1 microjoule and30 microjoules.
 30. A system for cataract surgery on an eye of apatient, comprising: a laser light source for generating a pulsed laserbeam; a laser delivery system including a multi-focal length opticalelement, wherein the multi-focal length optical element simultaneouslyfocuses a first portion of the pulsed laser beam at a first focal pointlocated at a first depth in the eye and a second portion of the pulsedlaser beam at a second focal point located at a second depth in the eyedifferent than the first depth; the laser delivery system furtherincluding an optical scanning system to scan the first and second focalpoints in at least a transverse direction; and control electronicsoperatively coupled to and configured to control the laser light sourceand the laser delivery system to scan the first and second focal pointsin the eye to form incision in an eye tissue.
 31. The system of claim30, wherein the multi-focal length optical element includes lenses,mirrors, or diffractive optics.
 32. The system of claim 30, wherein themulti-focal length optical element includes a multi-segmented lenshaving at least two co-axially arranged segments which focus the pulsedlaser beam into the first and second focal points along a same axis. 33.The system of claim 30, wherein the multi-focal length optical elementincludes a multi-segmented lens having at least two off-coaxiallyarranged segments which focus the pulsed laser beam into the first andsecond focal points along a same axis.
 34. The system of claim 30,wherein the control electronics is further configured to control theoptical scanning system to adjust depths of the first and second focalpoints and to scan the first and second focal points in a transversedirection.
 35. The system of claim 30, further comprising: an imagingsystem, coupled to the control electronics, to acquire image data fromlocations distributed throughout a volume of a crystalline lens of theeye and construct one or more images of at least a portion of thecrystalline lens from the image data; wherein the control electronics isfurther configured to identify a cutting region based on the image data,the cutting region defining an anterior cutting boundary and a posteriorcutting boundary and including a portion of the crystalline lens,wherein the posterior cutting boundary is disposed anterior to the lensposterior capsule; and wherein the control electronics is configured tocontrol the laser delivery system based in part on the image data and ascanning pattern, to scan the first focal point and the second focalpoint within the cutting region.
 36. The system of claim 35, wherein theimaging system is an optical coherence tomography system.
 37. The systemof claim 35, wherein the control electronics is further configured toreceive input from an operator regarding one or more parameters of thescanning pattern.
 38. The system of claim 30, wherein laser light sourcegenerates the pulsed laser beam having a pulse repetition rate between 1kHz and 1,000 kHz, and a pulse energy between 1 microjoule and 30microjoules.